Kiel 2004 – wissenschaftliches Programm
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EP: Extraterrestrische Physik
EP 1: Heliosph
ären- und Astrophysik
EP 1.4: Fachvortrag
Montag, 8. März 2004, 16:45–17:05, C
3D High resolution simulations of the Local Bubble: Modelling the OVI column density — •Dieter Breitschwerdt1,2 and Miguel A. de Avillez3 — 1MPI für extraterrestrische Physik, Garching, Germany — 2Institut für Astronomie, Universität Wien, Austria — 3Department of Mathematics, University of Évora, Portugal
The Local Bubble (LB) is an X-ray emitting region extending 100 pc in radius in the Galactic plane and 200 pc perpendicular to it and is embedded in a somewhat larger HI deficient cavity. The LB is the host of the Local Cloud which envelops the heliosphere. Therefore all in situ measurements are sensitive to the boundary conditions imposed by the Local Bubble. Spectroscopic measurements in the EUV and soft X-rays are inconsistent with standard LB models of a 106 K plasma in collisional ionization equilibrium. Simple models following the time-dependent ionization structure of an expanding superbubble, generated by multi-supernova explosions are in good agreement with X-ray and EUV observations. But all models fail to reproduce the observed low OVI absorption column density of ∼ 1.6 × 1013 cm−2. We have therefore performed 3D high resolution (down to 1.25 pc) hydrodynamic simulations of the Local Bubble in a realistic inhomogeneous ISM background medium, disturbed by supernova (SN) explosions at the Galactic rate. The Local Bubble is then the result of 20 SNe within the last 13.5 Myr. The resulting temperature distribution is monitored in Ovi and found to be in excellent agreement with OVI absorption line data.